The present invention relates generally to wound wires and the polymeric treatment thereof, and more particularly, but not by way of limitation, to wound musical instrument strings and the hydrophobic polymeric treatment thereof. As used in this disclosure, the term wire includes metal and non-metal wires, strings, ropes, cords, filaments and other similar structures.
One traditional design for a musical instrument string is to have an axial core wire around which is wrapped a wrap wire to add mass to the string. Such strings are commonly used for guitars and are referred to as wound strings. When mounted and tensioned on a musical instrument, the acoustic qualities of an oscillating wound string depends on, among other features, the degree of freedom of movement the windings of the wrap wire have in sliding over the core wire and in sliding relative to adjacent windings. In order to have the designed amount of free movement, any friction or adhesion of the windings and the core wire must be minimized. To this end, designers of wound musical strings frequently select polished metal wires for the wrap wire and core wire because components made of such materials have smooth surfaces and low coefficients of friction.
However, musicians have frequently encountered one difficulty in the use of such wound strings. The sound quality deteriorates rapidly as a string is played. The useful life of a conventional wound string is much less that of a similar non-wound musical string. The problem is caused by the environment in which the string is used. Musicians"" hands convey moisture, water soluble acids and salts, skin particles and other debris to the surface of the wound string as it is being oscillated. This moisture, acids, salts and debris collects in the interstitial gaps and voids between adjacent windings and between the windings and the core wire. The moisture, acids and salts causes corrosion of the component surfaces of the wound string, while the debris mechanically interferes with the movement of the windings. Corrosion creates microscopic fissures in the surface of the wrap wire and core wire. These fissures significantly increase the resistance to free movement of the windings of the wound string. The acoustic effects vary, but include a deadening of the sound of the string and a frequent need to retune or replace the string. Thus, wound strings may have a relatively short playing life during which they provide the optimum sound.
Over the years a number of solutions have been suggested for this problem. For example, U.S. Pat. No. 4,539,228 to Lazarus discloses a treatment for wound strings. In the process disclosed in Lazarus, the microscopic pores, cavities and crevices of the surfaces of a wound string are filled with polymeric micro-particles which act as a dry lubricant by reducing the friction between the surfaces of the string. The suspended dry lubricant is conveyed into the interstitial gaps and voids in a solvent emulsification containing: the suspended dry lubricant particles, a carrier solvent, a moisture displacing agent and a rust inhibiting agent. Depending on the formulation, the carrier solvent may be a moisture displacing agent or a rust inhibiting agent. The string is soaked in the solvent emulsification for an extended time to allow the carrier solvent to flow the suspended dry lubricant particles into the various pores of the material and into the interstitial cavities of the wound string. The dry lubricant particles provide lubrication and moisture displacing agent and rust inhibitor limit the corrosion of the string, thus extending its life according to the disclosure. The disadvantage of the Lazarus method is that the liquid moisture displacing agent or rust inhibiting agent may flow out of the interstitial void or may soon be exhausted.
Other solutions are directed toward preventing moisture and solid debris from collecting in the interstitial gaps and voids between adjacent windings and between the windings and the core wire. One such solution that is currently used by some string companies is to coat the outer surface of the wound string with an impermeable barrier. For instance, the D""Addario String Company soaks its strings in lacquer then dries them in air, thus providing a fully lacquer coated wound string. A similar string is offered by Martin Guitar Company. The disadvantage of lacquer coated wound strings is that the exterior coating wears quickly and is susceptible to cracking.
Still another approach is that used by W. L. Gore and Associates, Inc. for its Elixir brand strings. The Elixir brand strings are wound with a TEFLON(copyright) film which covers the string. The Elixir technology is described in U.S. Pat. Nos. 5,883,319; 5,801,319; 5,907,113 and 6,248,942. The Elixir process involves a complex manufacturing process first requiring the manufacture of the TEFLON film and then the wrapping and adhesion of the film to the wound strings. Additionally, such film may cause the acoustic quality of the wound string to be deadened.
Accordingly, there is a continuing need in the arts for an economical and procedurally simple solution to the problem of preventing moisture, acid and salts from causing corrosion of the windings and the core wire, and to the problem of solid debris collecting in the interstitial voids between the windings and the core wire.
A hydrophobic polymeric material is coated on the surfaces of the wound string within the interstitial voids between the string windings and between the winding and the core wire, while the exterior surfaces remain uncoated. The hydrophobic polymer prevents or reduces corrosion by repelling moisture and by forming barriers to the introduction of moisture and debris into the interstitial voids. The polymer is applied by soaking the majority of the length of the string in a liquid polymeric solution, situated in a holding tank, for a time sufficient to allow for proper penetration of the solution into the interstitial voids. The string is removed from the bath. The residual liquid polymeric solution is removed from the exterior surface of the wound string by use of a resilient scraper. The string is hung to dry for 8 hours in a clean room environment at ambient temperatures and, more preferably, maintained at a temperature of between 20xc2x0 C. and 25xc2x0 C. Alternatively, the string is treated by a combination of heat and drying. The end result is a string whose tonal quality and useful life is extended.
Accordingly, it is an object of the present invention to provide an improved treatment for wound strings which will protect the string from the corrosion caused by the accumulation of moisture, acids and salts in the interstitial gaps and voids between adjacent windings and between the windings and the core wire.
Another object of the invention is the provision of a string treatment process which will reduce the accumulation of moisture, acids and salts and solid debris in the interstitial gaps and voids between adjacent windings and between the windings and the core wire.
Another object of the invention is the provision of a string treatment process which is simple to apply.
Another object of the present invention is the provision of economical processes for treatment of wound strings.
Other and further objects features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the following disclosure when taken in conjunction with the accompanying drawings.